The design of this variant is based on the old Rogue Trader MkVI helmet. It's by far the least popular variant but its is an official design (below is a newer Forge World model)

of course the later patterns of the MkVI helmet look much more interesting with the vertical vents.
I was hoping that they would add this variant in time but that dream died a long time ago.

I really wonder why the company which did the, by the way outsourced, modelling work used the least favourable design as a template. All in all they, i.e. the 3D-art company, worked sloppy on any level with the templates they had at hand. I mean when its a game based on miniatures, you have to be aware that details like scale and design have to be correct 100 %. It's not a look-alike-contest. The virtual models should be identical to the actual plastic models (of course with scale adjustments to be able to move etc, but not design wise).
Having said this, the MkVI helmet in the game is one of the few which is correct (for that particular pattern) all others (apart from the Mk7) are miles off the target and had to be heavily modified by Noah to be even remotely close to what they should represent...but even he couldn't do wonders.